5000 IU is very high, might be beneficial during the winter for folks with very fair skin. but most probably shouldn't take that much every day
You got it backwards, it would be more beneficial in areas with few hours of sun for darker skin folks, since they do not absorb as much Vitamin D as fair skin folk do.
That's equivalent to about 10 minutes of sun exposure. Not very much when you look at it that way.
I think you mean for those with very dark skin, not fair?
You mean very dark skin?
It's my understanding that northern Europeans evolved fair skin in order to cope with the lack of vitamin D in their diet.